The problem was longitude. For most of the age of sail, mariners could determine their latitude, or north-south position, straightforwardly enough by measuring the height of the noonday sun above the horizon. Longitude, the east-west position, was substantially harder. It required knowing precisely what time it was at a fixed reference point on land, and [...] The post A self-taught Yorkshire carpenter’s son spent forty years building four increasingly precise sea clocks to solve a navigation pr